Mobile ground preparation machines of this type are cold milling machines, stabilizers, surface miners, and recyclers, in particular, which are used in the construction of paved traffic areas and are included below in the term “ground milling machines”. The working implements consist of a milling drum that is provided with a plurality of cutting tools, more particularly milling bits. The cutting tools are usually disposed along spiral lines on the surface of the milling drum, which spiral lines correspond to a left-hand thread on one half of the milling drum and to a right-hand thread on the other half of the same. As a result of this orientation of the spiral lines, material that has been milled off is conveyed inwardly to the center region of the milling drum, in the case of cold milling machines and surface miners, due to the rotation of the drum. The ejector units are disposed in this region and are distributed over the periphery of the milling drum such that the milled material is flung out away from the drum and “shoveled” by means of the ejector units onto a conveyor belt for removal from the milling site. In the case of stabilizers and recyclers, the ejector plates are used for mixing the milled material. The ejector plates are subjected to attrition forces and must therefore be replaced regularly. A milling drum comprising ejector units of this type is described in DE 102009014729 B3, for example.
For reasons of weight optimization and cost, efforts are made towards providing the ejector plate with the least possible material thickness. The problem frequently encountered in the use of these light-weight ejector plates is that they become deformed and wear out under stress conditions, which restricts their operability. One particular problem in this respect relates to the region in which the ejector plates are attached to the basic unit and in which the material is weakened, for example, by holes provided for a bolted connection. However, any deformation of the material is in this region particularly undesirable, since a deformed ejector is difficult to remove from the basic unit for the purpose of replacement.
A further problem relates to the widespread use of ejector plates not made by the original manufacturer, which have insufficient strength properties as a replacement part.